Style drills

Rewrite each code block to comply with the class style guide.

1. x < - c( 1,-2,3,-4,5,NA )
     y < - x * - 1
     y[ y>0 ]
   

   x <- c(1, -2, 3, -4, 5, NA)
   y <- x * -1
   y[y > 0]
   

2. n = 1
   mycondition <- round (runif (1,0,1,))
   if( mycondition ) {
       n <- n + 1
       print(paste("n =" , n , sep=" "))
   } else {
   print("false")
   }

   n <- 1
   my_condition <- round(runif(1, 0, 1))
   if (my_condition) {
     n <- n + 1
     print(paste("n =", n, sep = " "))
   } else {
     print("false")
   }

3. # create a sequence from 1 to 50
   z <- seq(1,50)
   
   # test whether an observation is even
   even <- z%%2 = = 0
   
   # subset z by the test above
   z = z [even]
   
   # plot a histogram
   library( ggplot2 )
   qplot (z, geom="histogram", binwidth=1)

   z <- seq(1, 50)
   
   # test whether an observation is even
   even <- z %% 2 == 0
   
   z <- z[even]
   
   library(ggplot2)
   qplot(z, geom = "histogram", binwidth = 1)

4. mat <- matrix( c( 34, 23, 53, 6, 78, 93, 12, 41, 99 ) ,nrow = 3)
   df <- as.data.frame (mat)
   names( df ) <- c("score_given_to_car_on_driving_test", 
    "score.given.to.van.on.driving.test", 
     "score-given-to-truck-on-driving-test")

   mat <- matrix(c(34, 23, 53, 6, 78, 93, 12, 41, 99), nrow = 3)
   df <- as.data.frame(mat)
   names(df) <- c("car", "van", "truck")

5. library( ggplot2 )
     head(mpg)
   second_version_of_mpg <- mpg[ mpg$cyl = 6,]
   second_version_of_mpg$class <- as.character(mpg2$class)
   qplot(cty, hwy, data=second_version_of_mpg, geom="point", color=class ) +  geom_smooth( method = "lm", se=FALSE ) + opts (title="City vs. Highway MPG" )

   library(ggplot2)
   head(mpg)
   mpg2 <- mpg[mpg$cyl == 6, ]
   mpg2$class <- as.character(mpg2$class)
   qplot(cty, hwy, data = mpg2, geom = "point", color = class) + 
     geom_smooth(method = "lm", se = FALSE) + 
     opts(title = "City vs. Highway MPG")

6. mean <- function(x) {
   sum(x)/length(x)
   }
     

   mean <- function(x) {
     sum(x) / length(x)
   }